Mike,

With the D L at the end of the coax at the antenna, you can't get an 
accurate measurement of the S W R if you are going through the tuner in the 
coax 1 or coax 2 positions as these positions include the variable 
capacitors and inductors of the tuner in the circuit.

In order to troubleshoot properly, you need to break down the circuit to the 
minimum components in order to determine the problem area as follows: 
transmitter, short jumper to S W R bridge, short jumper to D L.  If this 
works then remove the second short jumper and replace it with the full 
length of coax to your antenna and move the D L to the antenna end of that 
coax and check again.  If things go bad now, it appears the long coax or one 
or both of its connectors are suspect.

Don't forget to measure the resistance of the D L to make sure it is OK.  If 
your test equipment is faulty, your chasseing your tail.
 What are you using as an S W R meter?

73

Howard

----- Original Message ----- 
From: "Mike Ryan" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, February 09, 2014 11:55 AM
Subject: 75m issue sum up


> Hi all:
>
> Here's a sum up of my issue and the tests I've done.
> 1ST off I got an MFJ-986 tuner which can switch to bypass for a dummy 
> load,
> 2 coax either direct or through tuner and a balance line which is not 
> used.
> My dummy load is connected to about a 3 foot length of coax and to the by
> pass on the tuner. The SWR on this is 1.0/1.
> When I removed the dummy load from the 3 foot length and connected it to
> the 100 foot length of coax at the base of my antenna, in coax 1 and 2, I
> got a 30/1 SWR, didn't try direct 1 and 2 with the dummy load on the 100
> foot length.
> In direct 1 on 40M this morning, I got an SWR of 2.5/1. Every piece of 
> coax
> I've had in my 10 years as a ham, I've always got an SWR of 30/1 with an
> antenna connected before tuning. I've also gotten this type of figure when
> the dummy load was connected to the tuning circuit but not in the bypass. 
> I
> can only take from that my coax or connecters haven't been done properly
> over the years.
> On the actual issue I'm having, there's an SWR spike of 6/1 and its
> intermittent. It goes away for probably 45 minutes to an hour, then
> returns.
> The tuner used was connected to another antenna and was perfect on the
> bands it operates on and handled a KW with no issues. As soon as I pay for
> my Amp, I'm going to buy a brand new length of coax and see if that fixes
> things.
> The only thing I can recall is when I 1ST put up the antenna, I was using 
> a
> 75/80 foot length and there was no issues. I shortened it up because I
> thought is was to much laying on the ground and then the problems
> persisted.
>
> 73:
> Mike VO1AX